Field
The present application relates to an endoscope, in particular a video endoscope, with an adjustable viewing direction, with an endoscope shaft having a longitudinal axis, wherein in the endoscope shaft a first optical unit, with a prism pivotable about a pivot axis in order to deflect light, is provided and a second optical unit, with at least one fixed prism for deflecting light, which is deflected by the pivotable prism of the first optical unit, is arranged in a direction parallel to the longitudinal axis of the endoscope shaft, wherein the pivotable, prism, which can be a distal prism, has a light exit surface facing towards the prism, which can be a proximal prism, of the second optical unit, and the prism of the second optical unit has a light admission surface facing towards the light exit surface of the pivotable prism, such as by being oriented in parallel.
Prior Art
Endoscopes, and in particular video endoscopes, in which the light of an operative field entering a distal tip of an endoscope shaft of the endoscope is directed through an optical system onto one or more image sensors, are known in different designs. Thus, there are endoscopes with a straight-ahead view, a so-called 0° viewing direction, or endoscopes with a lateral viewing direction, which have for example a lateral viewing direction of 30°, 45°, 70° or the like deviating from the 0° viewing direction. In this context, the degree numbers indicate the angle between the central viewing axis and the longitudinal axis of the endoscope shaft. Further, there are endoscopes or respectively video endoscopes with an adjustable lateral viewing direction, in which the viewing angle, i.e. the deviation from the straight-ahead view, is adjustable.
When adjusting the viewing angle, the deviation from the straight-ahead view, in particular in relation to the longitudinal axis of the endoscope shaft, is thus changed.
EP 2 369 395 A1 further shows an optical system for a video endoscope in which a change in the viewing angle occurs such that a prism of a prism unit with three prisms is turned about a rotary axis which lies perpendicular or respectively transverse to the longitudinal axis of the endoscope shaft. The two other prisms, which define the optical light path together with the first prism, are not rotated so that the reflection surface of the first prism, which is turned, is twisted with respect to the corresponding reflection surface of the second prism.
Another endoscope with variable viewing direction is described in DE 10 2010 028 147 A1.
Reference will now be made to FIGS. 1-3 from DE 10 2012 202 552 A1 disclosing a video endoscope of the prior art. FIG. 1 shows a schematic perspective representation of a video endoscope 1 with a proximal handle 2 and a rigid endoscope shaft 3. A viewing window 5 is arranged on the distal tip 4 of the endoscope shaft 3, behind which a distal section 6 of the endoscope shaft 3 is arranged, which has a prism unit (not shown) and an image sensor unit (not shown).
The viewing window 5 on the distal tip 4 is designed curved and asymmetrical. In particular, the viewing window 5 is designed spherically curved in one design. The viewing window 5 is thus designed to support a variable lateral viewing angle. A change in the viewing direction, i.e. a change in the azimuth angle about the longitudinal axis of the endoscope shaft 3, is effectuated by a turning of the handle 2 about the central axis of rotation or respectively longitudinal axis of the endoscope shaft 3. The jacket tube of the endoscope shaft 3 is connected with the handle. The prism unit (not shown) on the distal tip 4 also rotates with the turning of the handle 2.
The handle 2 has a first control element designed as a rotary wheel 7 and a second control element designed as a sliding switch 8.
For retaining the horizontal position of the displayed image, the rotary wheel 7 is held tight while turning the handle 2. This causes the image sensor inside the endoscope shaft 3 to not make the movement.
The sliding switch 8 is moved in order to change the viewing angle, i.e. the deviation of the viewing direction from the straight-ahead view. A sliding of the sliding switch 8 distally leads for example to an enlargement of the viewing angle; a retraction of the sliding switch 8 proximally effectuates in this case a reduction in the viewing angle up to the straight-ahead view. The actuation of the sliding switch 8 involves a turning of the image sensor in order to retain the horizontal position of the displayed image even in the case of a twisting of the prism unit against each other.
FIG. 2 shows a corresponding prism unit 10 according to the state of the art schematically from the side. On the left side of the image, light from a central light path 21, which is shown as a dashed-and-dotted line, enters through a viewing window 5 of the endoscope shaft and enters a first, distal prism 12 of the prism unit 10 through a negative meniscus lens 11 designed as an admission lens. The light hits the mirrored surface 13 of the prism 12 and is reflected downward in the direction of a second prism 14 of the prism unit 10 as well as a mirrored surface 15 of the second prisms 14.
The mirrored surface 15 of the prism 14 has an acute angle to the bottom side 17 of the second prism 14 so that the central light path is first reflected onto a central section of the bottom side 17, which is also mirrored, and from there to a second mirrored surface 16 of the second prism 14. This second mirrored surface 16 also has an acute angle to the bottom side 17, so that the central light path is, in turn, reflected upwards (axis B). There, the light enters a third prism 18 of the prism unit 10 with a mirrored surface 19, through which the light of the central light path 21 is in turn reflected centrally in a direction parallel to the longitudinal axis of the endoscope shaft 3 and exits the prism unit 10 through an exit lens 20.
Moreover, another part of an optical fiber bundle 25 is shown above the prism unit 10, by means of which light is directed from the proximal to the distal tip in order to illuminate an otherwise unilluminated operative field.
The first prism 12 of the prism unit 10 is turned or respectively pivoted about the perpendicular axis A, which is also called the pivot axis, in order to adjust the lateral viewing angle. The mirrored surface 13 of the first prism 12 and the mirrored surface 15 of the fixed prism 14 of the prism unit 10 are thereby also rotated against each other so that the horizontal position of the image, which is forwarded proximally, is changed during a turning of the first pivotable prism 12 about the axis A. This must be counterbalanced by a turning of the image sensor or the image sensors. FIG. 3 shows the prism unit 10 from FIG. 2 in a schematic top view. The first prism 12 is arranged in a 0° viewing direction. The first prism 12 is pivotably mounted about the pivot axis A together with the negative meniscus lens 11. In this case, the overlapping area is twisted between the mirrored surfaces 13 of the first prism 12 and 15 of the second prism 14. A turning of the horizon, which will be explained below, takes place in the case of a rotary or respectively pivoting movement of the first prism 12.